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Tobias Heilmann
xraid - speed factors
on Sep 6, 2007 at 4:08:08 pm

I have spent the last hour reading threads and archives... perhaps I missed the key info...

I have a Dual Core 2.0 Ghz Power PC.
OS 10.4.1
FCP 5.1.4
QT 7.2

a Kona3 Card with the latest driver,

and an xraid connected via apples dual channel fibre channel card (copper cables) with the latest firmware.

Capturing 1080psf 29.97 8 Bit via HDSDI is a no go. Dropped frames.

Checking the xraid with AJA Kona System Test, I can see that write speeds drop down to 50 MB/s on the large 4GB files.

I am using (4) 750GB Modules on each xraid controller. Configured with Disk Utility as Raid 50.

What other factors could slow me down so much?

Thanks in advance.

Tobias

In Touch Media Entertainment
Munich, Germany


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szumlins
Re: xraid - speed factors
on Sep 7, 2007 at 1:55:22 am

cache flushing turned on or off?


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Bob Zelin
Re: xraid - speed factors
on Sep 7, 2007 at 2:36:24 am

you need about 210mb/sec to do uncompressed 8 bit HD. I am sorry that you are stuck with the XServe RAID - because with 14 drives, it barely does this speed. I have no idea what it does with 8 drives (you do have 8 drives, not 4 - correct) - but if you run AJA Kona System Test, you will see that your internal boot drive on your MAC is faster than 50mb/sec. You could bet better performance with any cheapo FW800 drive.

To do uncompressed HD, you can get any number of SATA, Fibre, or SCSI arrays from companies like Cal Digit, Dulce, Sonnet, Ciprico, and so many others, for a fraction of the price of the XServe RAID (and you should have 14 drives for uncompressed HD on the XServe RAID). But as for your 50mb/sec - well, as has just been suggested, go into RAID ADMIN, and check your CACHE FLUSHING, but this is REAL SLOW, and I doubt that this is a CACHE FLUSHING issue. One of the drives is bogging down the entire array, and it is almost impossible to diagnose a single drive problem on an XServe RAID - the RAID Admin will not test individual drives (and Apple support will be no help - you dont' believe me, but you will see once you call them).

SO, what would I do ? Run AJA Kona System test, select a 4 Gig file size and watch the LED's on the front of the XServe RAID, see if one of the lights stays on SOLID, instead of flashing away like the other drives. The one that is solid is probably a flakey drive, and needs to be yanked out (go ahead, it's RAID 50, you won't lose nothing, and you are SCREWED at 50mb/sec, anyway).


Bob Zelin


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Tobias Heilmann
Re: xraid - speed factors
on Sep 7, 2007 at 5:51:31 am

Bob. Thank you.

Yes, it is (8) Drives. Yes, Cache Flush is turned off. Valid point on not having (14) drives, perhaps I should stock up.

Buying a different raid unfortunantely is not an option at the moment.

How would upping to FCP 6 (we also have Quad 3Ghz Mac Pro) and using the new ProRes HD Codec solve my problem? At all?

Could the coice of expansion slots also have to do with this problem?

Thank you!

Tobias


In Touch Media Entertainment
Munich, Germany


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